A multimode wireless device supports multiple RATs (radio access technologies) and typically operates on multiple frequency bands. As a first example, a wireless device might support GSM/GPRS/EDGE (Global System for Mobile communications/General Packet Radio Service/Enhanced Data rates for GSM Evolution), UMTS/HSPA (Universal Mobile Telecommunications System/High-Speed Packet Access), and CDMA2000 1x/1xEV-DO (Code Division Multiple Access 2000 1x/1x Evolution-Data Optimized or 1x Evolution-Data only). As a second example, a wireless device might support GSM/GPRS/EDGE, and UMTS/HSPA. Other wireless devices might support a different set of RATs.
Most regulated licensed frequency bands are typically allocated to be used by multiple air interfaces (or equivalently multiple RATs) as shown in the following table.
Frequency BandAir Interfaces (RATs)(downlinkcdma2000 1x/frequency)GSM/GPRS/EDGEUMTS/HSPA1xEV-DO 869-894 MHzknown cellular 850 MHzknown as band Vknown as band class 0bandor NA cellular band1930-1990 MHzknown as PCS 1900 MHzknown as band IIknown as band class 1bandor PCS band 925-960 MHzknown as E-GSMknown as band VIII,known as band class 9currently being(not deployed yet)deployed2100-2170 MHzNoknown as band Iknown as band class 6(not deployed yet)1805-1880 MHzknown as GSMknown as band III (notknown as band class 81800deployed yet)(not deployed yet)For example, a 60-MHz-wide PCS band and 25-MHz-wide cellular band can be split into multiple blocks and allocated to a first provider (GSM/GPRS/EDGE+UMTS/HSPA operator), a second provider (cdma2000 1x/1xEV-DO operator), and a third provider (GSM operator).
A wireless device acquires a network of a given RAT by using a transceiver that is specific to the RAT in order to receive service. As indicated in the table above, each RAT typically operates on multiple frequency bands. Therefore, there are numerous possibilities in terms of supported frequency bands and supported RATs. A wireless device might scan all of the supported frequency bands and all of the supported RATs in order to search for a network. With the introduction of more frequency bands and RATs, the amount of network scanning that a multi-mode device performs can become excessive. Excessive network scanning is undesirable because it takes time, consumes battery power, occupies communication resources, introduces latency to provide service, etc.